Numerical simulations of the dark universe: State of the art and the next decade

Kuhlen, M.; Vogelsberger, Mark; Angulo, Raúl E.

doi:10.1016/j.dark.2012.10.002

Cited by 192 publications

(185 citation statements)

References 419 publications

(588 reference statements)

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“…Here, we describe three discrepancies, and show how two of them may point beyond CCDM in the form of DM self-interactions. We emphasize, however, that the situation remains far from clear, and ultimately more detailed numerical simulations including baryonic effects are required before drawing definitive conclusions [27,28].…”

Section: Self-interacting Dark Matter and Small Scale Structurementioning

confidence: 99%

Beyond collisionless dark matter: Particle physics dynamics for dark matter halo structure

2013

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Dark matter (DM) self-interactions have important implications for the formation and evolution of structure, from dwarf galaxies to clusters of galaxies. We study the dynamics of self-interacting DM via a light mediator, focusing on the quantum resonant regime where the scattering cross section has a non-trivial velocity dependence. While there are long-standing indications that observations of small scale structure in the Universe are not in accord with the predictions of collisionless DM, theoretical study and simulations of DM self-interactions have focused on parameter regimes with simple analytic solutions for the scattering cross section, with constant or classical velocity (and no angular) dependence. We devise a method that allows us to explore the velocity and angular dependence of self-scattering more broadly, in the strongly-coupled resonant and classical regimes where many partial modes are necessary for the achieving the result. We map out the entire parameter space of DM self-interactions -and implications for structure observations -as a function of the coupling and the DM and mediator masses. We derive a new analytic formula for describing resonant s-wave scattering. Finally, we show that DM self-interactions can be correlated with observations of Sommerfeld enhancements in DM annihilation through indirect detection experiments.

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Section: Self-interacting Dark Matter and Small Scale Structurementioning

confidence: 99%

Beyond collisionless dark matter: Particle physics dynamics for dark matter halo structure

2013

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“…The current state-of-theart cosmological hydrodynamic simulations such as the Illustris Simulation ) and the Eagle Simulation have significantly advanced our understanding of the highly nonlinear processes of galaxy formation. However, while N -body simulations performed with different codes produced consistent properties of the dark matter halos (e.g., Diemand et al 2008;Springel et al 2008;Stadel et al 2009;Kim et al 2014) and large-scale structures (e.g., Springel 2012; Kuhlen et al 2012), hydrodynamic simulations using different numerical methods and physical models have not been able to achieve such a consensus. On the cosmic scale, while the Illustris Simulation, which used the moving-mesh code Arepo (Springel 2010a), and the Email:qxz125@psu.edu Eagle Simulation, which used a variant of the smoothed particle hydrodynamics (SPH) code Gadget (Springel et al 2001;Springel 2005), show overall agreement on the global star formation history (Sparre et al 2015;Schaye et al 2015) and stellar mass functions Furlong et al 2015), significant discrepancies remain in a number of galaxy properties such as galaxy color bimodality Trayford et al 2015) and cluster gas fraction Genel et al (2014); Schaye et al (2015).…”

Section: Introductionmentioning

confidence: 99%

The Formation of a Milky Way-Sized Disk Galaxy. I. A Comparison of Numerical Methods

Zhu

2016

ApJ

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The long-standing challenge of creating a Milky Way-like disk galaxy from cosmological simulations has motivated significant developments in both numerical methods and physical models. We investigate these two fundamental aspects in a new comparison project using a set of cosmological hydrodynamic simulations of a Milky Way-size galaxy. In this study, we focus on the comparison of two particle-based hydrodynamics methods: an improved smoothed particle hydrodynamics (SPH) code Gadget, and a Lagrangian Meshless Finite-Mass (MFM) code Gizmo. All the simulations in this paper use the same initial conditions and physical models, which include star formation, "energy-driven" outflows, metaldependent cooling, stellar evolution and metal enrichment. We find that both numerical schemes produce a late-type galaxy with extended gaseous and stellar disks. However, notable differences are present in a wide range of galaxy properties and their evolution, including star formation history, gas content, disk structure and kinematics. Compared to Gizmo, Gadget simulation produced a larger fraction of cold, dense gas at high redshift which fuels rapid star formation and results in a higher stellar mass by 20% and a lower gas fraction by 10% at z = 0, and the resulting gas disk is smoother and more coherent in rotation due to damping of turbulent motion by the numerical viscosity in SPH, in contrast to the Gizmo simulation which shows more prominent spiral structure. Given its better convergence properties and lower computational cost, we argue that MFM method is a promising alternative to SPH in cosmological hydrodynamic simulations.

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“…[322] for a recent review on N-body simulations). Nowadays, supercomputers are capable of following the evolution of billions to trillions of particles in cosmological volumes; however, upcoming observational missions place higher and higher demands on the realism required by cosmological codes.…”

Section: Simulating the Universementioning

confidence: 99%

BeyondΛCDM: Problems, solutions, and the road ahead

Bull

Akrami

Adamek

et al. 2016

Physics of the Dark Universe

441

210

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Despite its continued observational successes, there is a persistent (and growing) interest in extending cosmology beyond the standard model, ΛCDM. This is motivated by a range of apparently serious theoretical issues, involving such questions as the cosmological constant problem, the particle nature of dark matter, the validity of general relativity on large scales, the existence of anomalies in the CMB and on small scales, and the predictivity and testability of the inflationary paradigm. In this paper, we summarize the current status of ΛCDM as a physical theory, and review investigations into possible alternatives along a number of different lines, with a particular focus on highlighting the most promising directions. While the fundamental problems are proving reluctant to yield, the study of alternative cosmologies has led to considerable progress, with much more to come if hopes about forthcoming high-precision observations and new theoretical ideas are fulfilled.Keywords: cosmology -dark energy -cosmological constant problem -modified gravitydark matter -early universe Cosmology has been both blessed and cursed by the establishment of a standard model: ΛCDM. On the one hand, the model has turned out to be extremely predictive, explanatory, and observationally robust, providing us with a substantial understanding of the formation of large-scale structure, the state of the early Universe, and the cosmic abundance of different types of matter and energy. It has also survived an impressive battery of precision observational tests -anomalies are few and far between, and their significance is contentious where they do arise -and its predictions are continually being vindicated through the discovery of new effects (B-mode polarization [1] and lensing [2,3] of the cosmic microwave background (CMB), and the kinetic Sunyaev-Zel'dovich effect [4] being some recent examples). These are the hallmarks of a good and valuable physical theory.On the other hand, the model suffers from profound theoretical difficulties. The two largest contributions to the energy content at late times -cold dark matter (CDM) and the cosmological constant (Λ) -have entirely mysterious physical origins. CDM has so far evaded direct detection by laboratory experiments, and so the particle field responsible for it -presumably a manifestation of "beyond the standard model" particle physics -is unknown. Curious discrepancies also appear to exist between the predicted clustering properties of CDM on small scales and observations. The cosmological constant is even more puzzling, giving rise to quite simply the biggest problem in all of fundamental physics: the question of why Λ appears to take such an unnatural value [5,6,7]. Inflation, the theory of the very early Universe, has also been criticized for being fine-tuned and under-predictive [8], and appears to leave many problems either unsolved or fundamentally unresolvable. These problems are indicative of a crisis.From January 14th-17th 2015, we held a conference in Oslo, Norway to surve...

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Numerical simulations of the dark universe: State of the art and the next decade

Cited by 192 publications

References 419 publications

Beyond collisionless dark matter: Particle physics dynamics for dark matter halo structure

Beyond collisionless dark matter: Particle physics dynamics for dark matter halo structure

The Formation of a Milky Way-Sized Disk Galaxy. I. A Comparison of Numerical Methods

BeyondΛCDM: Problems, solutions, and the road ahead

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